Many products are produced in an air-tight manner for environmental, health, freshness, operational and/or other reasons. To meet the need for air-tight products, test equipment have been developed to test certain types of products for leaks. For example, U.S. Pat. No. 5,861,546 ('546 Patent) to Sagi et al., the disclosure of which is hereby incorporated by reference, discloses a leak detection apparatus that is suitable for detecting leaks in a product having an opening to which a leak sensor and a vacuum system may be coupled in order to form a closed test system. Once coupled to the opening of the product, the vacuum system exerts a low vacuum on the product thus resulting in gas flow from the product through the leak sensor to the vacuum system. Assuming that the product does not have a gross leak, the pressure within the product and the pressure maintained by the vacuum system will eventually equalize and enter a steady state condition. Once equalization occurs, the leak sensor determines the steady state mass flow rate for the gas flow between the product and the vacuum system which is indicative of the level of leakage occurring in the closed test system. Assuming all leakage in the closed test system is attributable to the product under test, a detected mass flow rate of zero would indicate the product contains no leaks, a small mass flow rate would indicate the product contains a small leak, and a larger mass flow rate would indicate the product contains a larger leak. The leak sensor then determines a test result based upon the mass flow rate and predetermined tolerances.
One disadvantage of the leak detection system of the '546 Patent is that the product to be tested is generally required to include some sort of opening to which the leak sensor and the vacuum system may be coupled in order to form the closed test system. While certain products such as automotive engines and heat exchangers include openings to which the leak sensor and the vacuum system may be coupled, many other products do not include such an opening. For example, many medical products are distributed and stored in sealed, air-tight packages in order to maintain freshness, maintain sterility, and/or prevent harm to the surrounding environment. These packaged medical products by design do not include openings. Accordingly, these packaged medical products cannot be tested by the leak detection system of the '546 Patent in a non-destructive manner.
A need, therefore, exists for a method and apparatus that are suitable for testing sealed products (i.e. products that contain no openings) for leaks.